This application claims the benefit of German patent application No. 199 61 982.4, filed Dec. 22, 1999, herein incorporated by reference.
The present invention relates to a method of winding textile yarn packages of the type commonly referred to as cheeses in random windings. More particularly, the present invention relates to the performance of such a method on a bobbin winding machine having multiple winding stations (also referred to as winding heads) each having a winding drum for friction driving of a cheese being wound, and a means for generating slippage between the cheese and the winding drum for preventing pattern winding in possible pattern zones, wherein the diameter of the cheese is calculated from the known diameter of the winding drum and the measured numbers of revolutions of the winding drum and of the cheese.
The basic methodology described above is generally known (e.g., German Patent Publication DE 43 39 217 A1). In such method, the calculation of the cheese diameter is used, for example, for determining the time for exchanging the cheese for an empty tube as a function of the diameter. It is also known in connection with this method to determine the exchange of the cheese for an empty tube as a function of the length of the yarn which has been wound onto the cheese. Here, the length of the wound-up yarn is determined by counting the revolutions of the winding drum, which are multiplied by a known yarn length fed in the course of one revolution of the winding drum. The generation of a slippage in possible pattern zones is caused by switching on and off a motor which drives the winding drum. Within a preset range of the number of drum revolutions, the number of revolutions of the winding drum is relatively rapidly increased from the lower limit to the upper limit by turning on the motor, after which the motor is switched off again until the lower limit has been reached. Slippage is created during the acceleration of the motor.
The cheese is seated in a pivotable creel and is pressed against the winding drum at a bearing pressure. In an older, but yet unpublished patent application (German Patent Application DE 198 29 597 A1,) it is disclosed to lower the bearing pressure for generating slippage in the course of winding through pattern zones, which step can be perform alone or in connection with switching off and on the motor.
If in the course of such a method, it is intended to perform the exchange of the cheese independently of a nominal yarn length, this is relatively free of problems. Slippage does not play a decisive role in such case and, if needed, can also be taken into account by means of correction factors, which adjust the result of the speed sensor, for example an incremental counter, by the amount of slippage.
However, problems arise if it is intended to perform an exchange of the cheese as a function of the diameter, specifically if the diameter which can be set and at which a winding head should be stopped is reached within a pattern zone. In this case, the calculation of the diameter of the cheese based upon the actual number of revolutions of the cheese and the winding drum in conjunction with the known diameter of the winding drum can lead to errors of several millimeters. This case occurs quite often, because the time required for the passage through a pattern zone can be up to several minutes.
It is accordingly an object of the present invention to improve the winding methodology of the type described above in such a way that a more accurate determination of the cheese diameter is possible even in pattern zones, whereby it is possible to turn off the winding head at a predetermined diameter of the cheese.
In accordance with the present invention, the actual diameter of the cheese during the passage through a pattern zone is determined by calculating the course of the increase of the cheese diameter to be expected and adding the diameter increases resulting during the passage through the pattern zone to the diameter of the cheese calculated prior to reaching the pattern zone from the ratio of the numbers of revolutions of the cheese and the winding drum to the diameter of the winding drum.
In this way, it is possible to draw relatively accurate conclusions regarding the actual diameter of the cheese even during the passage through the pattern zone and, if required, to shut down the respective winding head when a predetermined diameter has been reached.
In accordance with one feature of the invention, the course of the increase of the diameter of the cheese over time is calculated, and the time in the course of the passage through a pattern is registered. It is thus possible by means of the detected length of time to draw relatively accurate conclusions regarding the diameter of the cheese present during this period of time. It is then possible to preset a length of time at which the nominal cheese diameter is expected to be reached and to shut down the winding head at the end of this period of time.
In another further development of the invention, the course of the increase of the diameter of the cheese is calculated from the ratio of the wound-up yarn length and the calculated diameter, and during a passage through a pattern zone the length of yarn wound up is registered. This process can be attained simply by determining the length of wound-up yarn by means of registering the revolutions of the winding drum. In this case, it is assumed that the length of yarn or thread moved per revolution of the winding drum is known. If in accordance with this feature the nominal diameter of the cheese is reached during the passage through a pattern zone, it is the result of the diameter calculated prior to reaching the pattern zone and a predeterminable number of revolutions of the winding drum.
The diameter calculated from the course of the increase to be expected is used for outputting the actual diameter of the cheese finished in the course of the passage through the pattern zone. It is possible in this way to prevent the association of incorrect or erroneous diameter information with such cheeses. This is also advantageous when the exchange of the cheese is to be performed as a function of a nominal yarn length. The output of the diameter can take place in the form of a printout. Further output options may also be to show the diameter on a display or by means of a monitor.
Further characteristics and advantages of the invention will be described and understood from the following description of an exemplary embodiment with reference to the accompanying drawing.